Featured Research

from universities, journals, and other organizations

'Junk' DNA Now Looks Like Powerful Regulator, Scientists Find

Date:

April 24, 2007

Source:

Stanford University Medical Center

Summary:

Large swaths of garbled human DNA once dismissed as junk appear to contain some valuable sections, according to a new study by researchers at the Stanford University School of Medicine and the University of California-Santa Cruz. The scientists propose that this redeemed DNA plays a role in controlling when genes turn on and off.

Share This

Large swaths of garbled human DNA once dismissed as junk appear to contain some valuable sections, according to a new study by researchers at the Stanford University School of Medicine and the University of California-Santa Cruz. The scientists propose that this redeemed DNA plays a role in controlling when genes turn on and off.

Related Articles

Gill Bejerano, PhD, assistant professor of developmental biology and of computer science at Stanford, found more than 10,000 nearly identical genetic snippets dotting the human chromosomes. Many of those snippets were located in gene-free chromosomal expanses once described by geneticists as "gene deserts." These sections are, in fact, so clogged with useful DNA bits - including the ones Bejerano and his colleagues describe - that they've been renamed "regulatory jungles."

"It's funny how quickly the field is now evolving," Bejerano said. His work picking out these snippets and describing why they might exist will be published in the April 23 advance online issue of the Proceedings of the National Academy of Sciences.

It turns out that most of the segments described in the research paper cluster near genes that play a carefully orchestrated role during an animal's first few weeks after conception. Bejerano and his colleagues think that these sequences help in the intricate choreography of when and where those genes flip on as the animal lays out its body plan. In particular, the group found the sequences to be especially abundant near genes that help cells stick together. These genes play a crucial role early in an animal's life, helping cells migrate to the correct location or form into organs and tissues of the correct shape.

The 10,402 sequences studied by Bejerano, along with David Haussler, PhD, professor of biomolecular engineering at UC-Santa Cruz, are remnants of unusual DNA pieces called transposons that duplicate themselves and hop around the genome. "We used to think they were mostly messing things up. Here is a case where they are actually useful," Bejerano said.

He suspects that when a transposon is plopped down in a region where it wasn't needed, it slowly accumulated mutations until it no longer resembled its original sequence. The genome is littered with these decaying transposons. When a transposon dropped into a location where it was useful, however, it held on to much of the original sequence, making it possible for Bejerano to pick out.

In past work, Bejerano and his co-workers had identified a handful of transposons that seemed to regulate nearby genes. However, it wasn't clear how common the phenomenon might be. "Now we've shown that transposons may be a major vehicle for evolutionary novelty," he said.

The paper's first author, Craig Lowe, a graduate student in Haussler's lab at UC-Santa Cruz, said finding the transposons was just the first step. "Now we are trying to nail down exactly what the elements are doing," he said.

Bejerano's work wouldn't have been possible without two things that became available over the past few years: the complete gene sequence of many vertebrate species, and fast computers running sophisticated new genetic analysis software. "Right now it's like being a kid in a candy warehouse," Bejerano said. Computer-savvy biologists have the tools to ask questions about how genes and chromosomes evolve and change, questions that just a few years ago were unanswerable.

Bejerano and his colleagues aren't the first to suggest that transposons play a role in regulating nearby genes. In fact, Nobel laureate Barbara McClintock, PhD, who first discovered transposons, proposed in 1956 that they could help determine the timing for when nearby genes turn on and off.

Funding for the study came through Haussler, who is a Howard Hughes Medical Institute investigator.

Featured Research

Mar. 31, 2015  Researchers have illuminated an important distinction between mice and humans: how human livers heal. The difference centers on a protein called PPAR alpha which activates liver ... full story

Mar. 31, 2015  Researchers have recorded the first direct observations of the micro-scale mechanisms behind the ability of skin to resist tearing. The results could be applied to the improvement of artificial skin, ... full story

Mar. 31, 2015  Fewer than half of the physicians trained in the United States in 2013 received formal education or training on the subject of exercise, according to new research. "There are immense medical benefits ... full story

Mar. 31, 2015  Memory and as well as connections between brain cells were restored in mice with a model of Alzheimer's given an experimental cancer drug, researchers report. "With this treatment, cells under ... full story

Mar. 31, 2015  Increasing state alcohol taxes could prevent thousands of deaths a year from car crashes, say researchers, who found alcohol-related motor vehicle crashes decreased after taxes on beer, wine and ... full story

Mar. 31, 2015  Alcoholism takes a toll on every aspect of a person's life, including skin problems. Now, a new research report helps explain why this happens and what might be done to address it. "The clinical ... full story

Mar. 31, 2015  A new population of 'memory' immune cells has been discovered by scientists, throwing light on what the body does when it sees a microbe for the second time. This insight, and others like it, will ... full story

Mar. 31, 2015  Coronary heart disease and stroke, two of the leading causes of death in the United States, are diseases associated with heightened platelet reactivity. A new study in humans suggests an underlying ... full story

Mar. 31, 2015  A new study had researchers seeking answers to why the therapeutic benefit afforded by SSRIs was so limited in children and teenagers. If researchers can uncover the biological mechanisms preventing ... full story

Featured Videos

Solitair Device Aims to Takes Guesswork out of Sun Safety

Reuters - Innovations Video Online (Mar. 31, 2015)  The Solitair device aims to take the confusion out of how much sunlight we should expose our skin to. Small enough to be worn as a tie or hair clip, it monitors the user&apos;s sun exposure by taking into account their skin pigment, location and schedule. Matthew Stock reports.
Video provided by Reuters

Soda, Salt and Sugar: The Next Generation of Taxes

Washington Post (Mar. 30, 2015)  Denisa Livingston, a health advocate for the Dinι Community Advocacy Alliance, and the Post&apos;s Abby Phillip discuss efforts around the country to make unhealthy food choices hurt your wallet as much as your waistline.
Video provided by Washington Post

S. Leone in New Anti-Ebola Lockdown

AFP (Mar. 28, 2015)  Sierra Leone imposed a three-day nationwide lockdown Friday for the second time in six months in a bid to prevent a resurgence of the deadly Ebola virus. Duration: 01:17
Video provided by AFP

May 2, 2010  Researchers have discovered a new driving force behind cancer growth. New studies have identified how 'junk' DNA promotes the growth of cancer cells in patients with Hodgkin's ... full story

ScienceDaily features breaking news and videos about the latest discoveries in health, technology, the environment, and more -- from major news services and leading universities, scientific journals, and research organizations.